JPS61258881A - Radiation-curable pressure-sensitive adhesive composition - Google Patents

Abstract

PURPOSE:To provide the titled composition for surface-protection film, free of transfer to the adhered and having excellent weather-resistance, by compounding a specific liquid oligomer with an alkoxymethylated melamine compound having (meth)acryloyl group at a specific ratio. CONSTITUTION:The objective composition can be produced by compounding (A) 100pts.(wt.) of a liquid oligomer having unsaturated double bond in the molecule (especially preferably an oligomer having acrylic double bond in the molecule) with (B) 1-50pts. of an alkoxymethylated melamine compound imparted with (meth)acryloyl group (e.g. hexamethoxymethylmelamine).

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an adhesive composition for use in a surface protection adhesive film.

[Conventional technology]

Surface protection films are used to protect the surfaces of metal plates such as stainless steel plates and aluminum plates, painted metal plates, resin plates, glass, etc., but the basic characteristics required are:
The adhesive should adhere well to these coated bodies, and the adhesive should not transfer when peeled off. In order to maintain this irreversible property, a high degree of consideration is required since the surface preservation film is often exposed to harsh conditions such as high temperature or outdoor exposure during application and peeling. The adhesive commonly used for this purpose is one in which a polymer having a relatively high molecular weight and high viscosity is crosslinked to an extent that the adhesiveness is not lost, thereby increasing the cohesive force.

On the other hand, since the polymer is natural rubber, synthetic rubber, etc., it must be dissolved in an organic solvent and applied to the base material in the form of a solution.

However, in recent years, from the standpoint of pollution, safety, resource conservation, and energy conservation, the use of solvent-free products has attracted attention. As a solvent-free solution, radiation-curing adhesives that use liquid oligomers with unsaturated double bonds in their molecules are attracting attention.
Its properties are almost the same as those obtained using conventional polymer rubber.

[Problem that the invention seeks to solve]

However, since some unsaturated double bonds remain even after curing, it is often difficult to achieve a practical level of weather resistance, and improvement is desired.

JP-A-59-90568 proposed incorporating an N-methylol compound as a method for improving the weather resistance of radiation-curable adhesives, but systems with poor compatibility with liquid oligomers may cause stains on the adhesive surface. There is a problem that it transfers to the degami kimono and is easy to transfer.

The present invention was made in view of the above situation, and it is an object of the present invention to provide a radiation i-curable adhesive composition that has excellent compatibility with liquid oligomers and is difficult to transfer.

[Means for solving problems]

According to the present invention, such an object is achieved by irradiating a pressure-sensitive adhesive composition containing an alkoxymethylated melamine having an acryloyl (methacryloyl) group to a liquid oligomer having an unsaturated double bond to cause crosslinking. be done.

The radiation-curable liquid oligomers having an unsaturated double bond in the molecule used in the present invention include oligomers copolymerized with alkyl acrylates or alkyl methacrylates to a low degree of polymerization, polyol acrylates, These include acrylic oligomers such as polyester acrylate, urethane acrylate, and epoxy acrylate having one or more unsaturated double bonds per molecule at the end or side QVc, and reactive prepolymers such as polybutadiene, polychloroprene, and polyisoprene. Furthermore, the oligomer is liquid and solvent-free, so even if a C solvent is used, only a small amount is used.Furthermore, its viscosity is in the range of 102 cps to 5 x 10' cps at room temperature.

In the present invention, particularly preferred results are obtained with oligomers having highly reactive acrylic double bonds ((meth)acroyl groups) in the molecule.

Next, in the present invention, examples of the alkoxymethylated melamine to which a (meth)acryloyl group is imparted include methoxymethylated melamine and butoxymethylated melamine, and hexamethoxymethylmelamine is particularly advantageous. These melamines may be self-condensed, a mixture, or a co-condensed product. Next, an acrylate (methacrylate) having at least one hydroxyl group is used as a monomer imparting an acryloyl (methacryloyl) group.These monomers include ethylene glycol monoacrylate, propylene glycol monoacrylate,
These include diethylene glycol monoacrylate, polyethylene glycol monoacrylate, propylene glycol monoacrylate, polypropylene glycol monoacrylate, glycerin mono- or diacrylate, trimethylolpropane mono- or diacrylate, and their methacrylates. These may be used alone or in combination. Particularly preferred in the present invention are ethylene glycol monoacrylate and propylene glycol monoacrylate. The alkoxymethylated melamine and the above (meth)acrylate are subjected to an ether exchange reaction using a known method to introduce an alkoxymethylated melamine [(meth)acryloyl group, but it is necessary to exchange it with at least two or more 1-alkoxy groups. is necessary.

The acrylic-modified alkoxymethylated melamine (hereinafter abbreviated as acrylic-modified melamine) is the liquid oligomer 10.
It is added in an amount of 1 to 50 M parts per 0 parts by weight. If it is less than 1 part by weight, there is no effect, and if it is added more than 50 parts by weight, the weather resistance will not be improved.

In addition, chain transfer agents, tackifiers, softeners, antioxidants, fillers, fishing materials, etc. may be added to the above-mentioned pressure-sensitive adhesive composition depending on the required VC.

The radiation referred to in the present invention refers to active energy rays, such as α rays and β rays.
ionizing radiation such as rays, gamma rays, neutron beams, accelerated electron beams, and ultraviolet rays. Further, a curing accelerator may be contained in some cases, but when irradiating, particular attention must be paid to the irradiation atmosphere.

That is, since radicals generated by radiation irradiation are inhibited by oxygen in the air, depending on the case, it may be effective to replace the radicals with an inert gas such as nitrogen or to cover the film with a film or the like.

Examples will be explained in detail below. In addition, in the following, parts indicate parts by weight.

Example 1 80 parts of butyl acrylate, 20 parts of glycidyl methacrylate
A solvent-free acrylic copolymer was synthesized by bulk polymerization in the presence of a catalyst.

Next, 11!8 parts of acrylic was subjected to an addition reaction to synthesize an acrylic radiation-curable liquid oligomer (viscosity: 5 x 10'cps (25°C)) having an unsaturated double bond in the side chain.

Next, methoxymethylated melamine (manufactured by Hitachi Chemical ■,
To 100 parts of Melan 52.5), 548 parts of diethylene glycol monoacrylate, 1 part of 2-methylhydroquinone cL, and 1105 parts of paratoluenesulfonic acid were charged into a flask equipped with a stirrer, a thermometer, and a cooling condenser, and the mixture was reacted at 100°C. Ta. The end point of the reaction was defined as the point at which the reaction rate of ethylene glycol monoacrylate exceeded 90% as determined by liquid chromatography.

Next, to 100 parts of the above liquid oligomer, 5 parts of ethylene glycol dithioglycolate as a chain transfer agent, 20 parts of acryloyloxylethyl hydrogen phthalate (manufactured by Toagosei Kagaku ■, trade name 2M-5400), and 8 parts of acrylic modified methyl
A radiation-curable adhesive was prepared by adding 10 parts of gold. The adhesive was VC coated to a thickness of 5 μm on a 60 μm polyethylene film that had been corona-treated on one side.

Next, the IJ near filament type electron beam irradiation device (
Energy 5science Inc. (trade name: Electrocurtain) was used under a nitrogen atmosphere (oxygen concentration 500
The polymer was polymerized and reticulated by irradiation with an electron beam at a dose of 4 Mrad. Table 1 shows the characteristics test results of the obtained adhesive film for surface protection.

Example 2 An acrylic radiation-curable liquid oligomer was synthesized in the same manner as in Example 1 by copolymerizing 10 parts of ethyl acrylate, 75 parts of butyl acrylate, and 15 parts of glycidyl methacrylate, and further adding 85 parts of acrylic acid. did.

Next, methoxymethylated melamine (manufactured by Susumu Kagaku Kogyo ■,
Example 1: 580 g of ethylene glycol monoacrylate was added to 100 parts of Sumimaru M-100 (trade name: Sumimaru M-100).
Acrylic modified melamine was synthesized in the same manner.

10 parts of trimethylolpropane tris(β-thiopropionate) as a chain transfer agent per 100 parts of the above oligomer.
A radiation-curable adhesive was prepared by mixing 10 parts of di(2-methacryloyloxyethyl) phosphate and 10 parts of acrylic modified melamine as a monomer having an acidic group. Then, in the same manner as in Example 1, an entire polyethylene surface protection adhesive film was prepared by irradiating it with an electron beam. The test results are shown in Table 1.

Comparative Example 1 Acrylic modified melamine 1 in the adhesive in Example 1vC
A pressure-sensitive adhesive film was prepared in the same manner using a pressure-sensitive adhesive with only 0 parts removed. The test results are shown in Table 1, and there was some adhesion due to cohesive failure of the adhesive.

Comparative Example 2 In Example 1, unmodified methoxymethylated melamine (Melan 5) was used instead of acrylic modified melamine in the adhesive.
A pressure-sensitive adhesive film was prepared in the same manner except for adding 10 parts of 26). The results are shown in Table 1.

Comparative Example 3 In Example 2, 10 parts of acrylic modified melamine was replaced with unmodified methoxymethylated melamine (Sumimar M-100).
A pressure-sensitive adhesive film was prepared in the same manner except for 10 parts.

The results are shown in Table 1.

Table 1 1) J I 5-C-2107Vc semi-1. Measured with: (Adherent: 5US430BA plate) 2) Treated with a hot plate press at 80° C. under a pressure of 10 kg/(jt) for 24 hours, and observed changes such as transfer of the adhesive to the adherend.

5) The fcSUS-450BA board with the adhesive film fully pasted was treated for 100 hours using a due cycle sunshine weather meter (manufactured by Suga Test Instruments: model WEL-5UN-DCE) under the conditions of a black panel temperature of 63°C and a relative humidity of 50%. Observe changes such as transfer of the adhesive to the adherend.

○: Transfer and adhesion, △: Transfer due to seepage of monomer ×: Transfer due to cohesive failure of the adhesive [Effects of the invention] As is clear from the above, the post-irradiation curing adhesive composition of the present invention adheres. It does not transfer to the body, has excellent weather resistance, and is useful as an adhesive for surface preservation films.

Claims (1)

[Claims] 1. Liquid oligomer 10 having an unsaturated double bond in the molecule
A radiation-curable adhesive composition comprising 1 to 50 parts by weight of an alkoxymethylated melamine compound having a (meth)acroyl group added to 0 parts by weight.